st: truncreg:could not calculate numerical derivatives

Hi, all:
When I use truncreg to estimate truncated regression, this error always appear:
could not calculate numerical derivatives
missing values encountered
r(430);
I tried to begin with very simple model: just use one independent variable, but this error still exists. My database has more than 20k data, this may cause problem to find initial value for the model. I also tried to take a sample from this database(1%), like 200, the model works. But I need to use all my 20k data, is there a better way to estimate truncated regression?
Thank you all in advance.
-Fiona
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